The present invention relates generally to the field of stencils for use in the construction industry and, more specifically, to a template for marking entry holes for conduit, such as the type used by electricians for carrying electrical wires.
It is often necessary in the construction industry for electric wires to be carried within conduit, such as metal or plastic piping, for example, which may be of any of a wide variety of sizes and which is generally referred to in the trade by the size of the interior diameter of the pipe, in inches; i.e., the "trade size". The particular trade sizes commonly used have been standard in the industry in the United States and Canada for many years.
It is well known that in order for electricians to properly install such conduit they must frequently drill holes, commonly referred to as "entry" holes for receipt of the conduit, such as for entry of the conduit and wires therein into a panel forming one end of a wiring box, or through some other surface such as a wall or floor. Because the pipes (conduits) are referred to in the trade by inside diameter, which may include fractions of an inch, and because the hole which receives a given pipe must be large enough to accommodate the added dimension of the pipe's wall; i.e., adding another fraction of an inch, accurate and neat formation of the proper size(s) and number of pipe entry holes can become complex and extremely time consuming. This is particularly the case if a large number and variety of sizes of pipes are required, and especially if coaxial holes of the same size are also required, for example to permit exit through another, parallel, surface of at least some of the same conduits which entered the box.
Previously, this procedure was managed merely with the use of a pencil, a square and a standard ruler, laboriously and painstakingly measuring off each hole, taking into account the distance of the outside edge of the pipe from the edge of the surface through which a hole was to be made, the distance from the outside of the next closest pipe, the inside diameter of each pipe and the thickness of the pipe wall, as will be described in further detail later. If multiple rows and columns of pipes and/or various sizes thereof are necessary conduit entry hole formation becomes an extremely time consuming and tedious task due to the above-mentioned measurements and mathematical calculations. Furthermore, errors often occur as a result of the traditional method of hole marking, which errors result in duplication of effort as well as wasted material.
The template (or stencil) of the present invention, which may consist of one or two parts, is designed so as to greatly simplify and therefore speed up the above process with only the use of a pencil and the new stencil, which may be used in one or two parts depending upon the size of the hole to be made. Very little training is necessary for one to become familiar with the use of the new stencil for precise, accurate entry hole marking. Indeed for experienced carpenters or electricians familiar with the conventional procedure for forming conduit entry holes the new device is essentially self-explanatory and can become very rapid to use with just a little practice.
The present conduit entry template is formed with a smaller, central portion, for convenient use alone in marking entry holes for conduit of the most common sizes, and a larger exterior portion, into which the smaller portion fits fairly snugly and coaxially for use in marking entry holes for larger conduits. Thus, the central opening of the smaller template portion is used alone for marking the conduit hole center, whether the hole to be marked is small enough to mark with only the inner template portion, or so large as to require the addition of the larger, outer stencil portion.
The new stencil also is designed to take into account the differences in interior and exterior diameters of standard electrical conduit and thereby reduce marking errors which can readily occur due to miscalculation and/or confusion between the interior and exterior diameters of the pipe to be installed. The template of the present invention is provided with premeasured markings and numerals associated with those markings to indicate to the user the interior diameter of the conduit hole being marked. Openings formed through the template along the premeasured marks permit pencil marking of the hole edge for a hole sized appropriately for a conduit having an interior diameter (trade size) as selected and which automatically compensates for the additional distance needed to accommodate the standard thickness of the pipe wall.
A ruler marked in eighths of an inch is provided on at least one edge of each of the inner (interior) and outer (exterior) stencil portions so that a separate tool is not required to measure distances between adjacent hole edges and between the hole edges and a wall or panel edge.
The new stencil is also adapted to provide "cross hair" marks to guide use of a knockout hole cutter and to facilitate exact spacing between holes, regardless of diameter differences, and uniform spacing from a point on each hole edge to (for example) a panel edge which will be adjacent to a wall upon which the electrical box being marked is to be mounted.
Accordingly, it is among the goals of the present invention to provide a stencil for facilitating fast and accurate marking of the entry holes to be formed in a surface for passage therethrough of conduit of substantially any preselected size or sizes, for example, those in the range of from approximately one half to at least about 4 inches internal diameter (i.d.).
It is also among the goals of the present invention, having the above features, that use of the new template will result in accurate, neat hole markings, faster than previously possible, by allowing the user to reduce the number of measurements which must be made individually for every hole to be formed by the conventional conduit entry hole marking method.
It is further among the goals of the present invention, having the features indicated, that it be equally useful by people who are left-handed, as well as by those who are right-handed, and that the device be simple to use, without the aid of other tools, even by people with little or no training.
It is also among the goals of the new conduit entry hole template that it be suitable for manufacture with materials which are inexpensive and readily available and by facile and economical methods which are already known, as well as possibly by new methods, yet to be developed, and with the use of new materials, as yet unknown.
Accordingly, in keeping with the above goals and advantages, the present invention is, briefly, a template for facilitating marking of entry holes in a surface for passage therethrough of conduit. The template has a flat portion formed of semi-rigid material and two flat sides. The flat portion has a central opening and a plurality of markings on one side. The markings are parallel to a section of the perimeter and spaced inwardly at graduated distances therefrom. A plurality of slots are formed through the flat portion, spaced apart and parallel to one another, substantially coextensively with each corresponding one of the plurality of markings, to thereby permit a user of the template to make a mark through one of the slots to indicate an outer edge of a hole of a preselected size to be formed using the template.
Moreover, the invention is also, briefly, a method for marking entry holes to be formed in a surface for passage through the holes of conduit, the method includes applying the above template to the surface to be marked, marking an elongated straight line on the surface to be marked at a preselected distance from an edge of the surface to be marked, making a transverse mark at one end of the straight line to thereby indicate the outermost edge of a hole to be formed in the surface, marking through the central opening of the flat portion the center of the hole to be formed, and marking the edge of the hole to be formed by making a mark through a preselected one of the plurality of slots formed through the at least one flat portion.
The new method further includes, briefly, using a template such as above and which has four straight slots extending radially outwardly and spacedly from the central opening of the template, each slot being at 90.degree. from each adjacent slot, and extending outwardly toward the perimeter of the flat portion. And, making a mark on the surface thereof each one of the four straight slots extending radially outwardly from the central opening of the template.
Further advantages of the invention will be in part apparent and in part pointed out hereinbelow.